There are certain principles of church order which, your Committee consider, ought to be distinctly recognised and set forth, as of great importance for the maintenance of union among the Churches of our Communion.For well over 100 years, the churches of the Anglican Communion lived according to the rules listed in the section of the encyclical quoted above, with the churches joined one to the other in the mutual bonds of affection, but with respect to polity and governance, the various churches practiced the good old-fashioned virtue of minding their own business and not intruding into the affairs of other churches without permission.
1. First, that the duly certified action of every national or particular Church, and of each ecclesiastical province (or diocese not included in a province), in the exercise of its own discipline, should be respected by all the other Churches, and by their individual members.
2. Secondly, that when a diocese, or territorial sphere of administration, has been constituted by the authority of any Church or province of this Communion within its own limits, no bishop or other clergyman of any other Church should exercise his functions within that diocese without the consent of the bishop thereof.
3. Thirdly, that no bishop should authorise to officiate in his diocese a clergyman coming from another Church or province, unless such clergyman present letters testimonial, countersigned by the bishop of the diocese from which he comes; such letters to be, as nearly as possible, in the form adopted by such Church or province in the case of the transfer of a clergyman from one diocese to another.
See what Tobias says about the application of the rules in the encyclical in the Anglican Communion today.